The present invention relates to a display system for Chinese characters in particular to a system for displaying Chinese characters by using a hardware circuit.
In the conventional computers, most of the display of Chinese characters is by using a Chinese character software stored previously in the computer or the disc driver. When character code to be displayed is input, the Chinese character software identifies the character to be displayed being Chinese or English and then gets the pattern for said character. Thereafter, the pattern for said character is sent to the video RAM and displayed onto the screen by using a graphic method, that is, the Chinese character `graph` being plotted on the screen while in the graphic mode. A block diagram of the conventional Chinese display system is shown as follows: ##STR1##
However, conventionally, English is generally displayed in the text mode, that is, the English character code (generally the ASCII code) is memorized into the video RAM and then the display of said character is completed by locating the pattern for said character code from the CGROM directly in dependent on the character code in the video RAM by the hardware followed by displaying the pattern onto the screen. The procedure from the character code through the pattern converted and then to display is completed by a hardware circuit. The block diagrams of the conventional English display system are shown as follows: ##STR2##
From the above description, we can see that in the conventional Chinese character display, there must be a software support during the display procedure from the character code to the Chinese character pattern converted. The text mode wherein the Chinese pattern can be directly displayed from the Chinese character code memorized into the video RAM cannot be attained. In other words, the conventional Chinese character display system is not compatible with the hardware under the text mode (i.e., without the support from the software). Therefore, the conventional Chinese character display is not compatible with the English display in the text mode so that some English software developed by the English language countries while applying to the Chinese characters have to be modified to add-in a driver or the software programs in order to display the Chinese characters.
Besides, the software processing is a must in the conventional Chinese character display. For that reason the Chinese display is absolutely slower than the hardware display in the text mode.
In addition, in the conventional Chinese character display method much more memory space is occupied, For example, e.g., only 2K byte of the video RAM is needed to display a screen of 80.times.25 under the English text mode. However, due to the graphic mode used in the conventional Chinese character display, in the case of a Chinese character display of 16.times.15, a screen of 80.times.25 (40.times.25 in Chinese) needs 32K byte of the video RAM. Also, some space of the system main memory will be occupied by the software program for processing the display of the Chinese characters.
Furthermore, owing to the software processing is a must for the conventional Chinese character display, the CPU of the system will spend some time on processing the video interface and make the speed of the whole system slow down.
Recently, though a Chinese pattern ROM is commercially available which can store more than ten thousands of Chinese characters by use of a hardware circuit, said Chinese pattern ROM cannot identify whether the code is an English character or a Chinese character such that the effects of mix using the English and the Chinese still cannot be obtained. Therefore, the software processing manner is still adopted in the display of Chinese characters.